Finishing lined brake shoe



Sept 7, 1943- l. B. .JOHNSON ET Al. 2,328,650

FINISHING LINED BRAKE SHOE Filed Jan. 19, 1940 9 Sheets-Sheet l doN Izzi/onion.:-

Sept 7, 1943- 1. B. JOHNSON ET A1.

FINISHING LINED BRAKE SHOE 9 Sheets-Sheet 2 ,s mail W w a im ai. @BWM w ,6 @mm2 B 7 ma wif/f m wkn ZW .ILHU

35 293.2., e9 /6 y M,

Sept- 7, 1943- l. B. JOHNSON ET A1. 2,328,650

FINISHING LINED BRAKE SHOE Sept. 7, 1943.

F .4. 7 is? FL w l Blz/68]?,

55 :mano \o a o 97 w Esa-l' .99 @"4 Sept. 7, 1943. B'. JOHNSON ET Al.

FINISHING LINED BRAKE SHOE Filed Jan. 19,` 1940 9 snee'tS-sheet 5 mw l I S Q ///7 /f/// 7 s 6. 8 E l 0 5 M. 7 8 no 7 5 Q M 8 /V// Q. 3\\ rd 9 F o 9 SePt- 7, 1943- B. JOHNSON ETAL I 2,328,650

FINISHING LINED BRAKE SHOE Filed Jan. 19, 1940 9 Sheets-Sheet 6 dln/Zhan dim a1/'Zim bg *Wgm/ l. B. .JOHNSON` ET AL FINISHING LINED BRAKE SHOE Sept. 7, 1943.

Filed Jan. 19, 1940 Egt.

9 Sheets-Sheet '7 @ME mw @gis Sept. 7, 41941?. l. B. JOHNSON ET AL FINISHING LINED BRAKE SHOE 9 Sheets-Sheet 8 k Invenoms.-

Filed Jan. 19, 1940 HW/3h0??? La? Rizla. y M (H/Sys sept. 7, 1943. L B, JQHNSON ET AL 2,328,650

FINISHING' LINED BRAKE SHOE Filed Jan. 19, 1940 9 Sheets-Sheet -9 end areas ofthe brake lining;

einige; Fig. 4c shows separately one form of agrindersetting dial i Patented Sept. 7, 1943 UNITED f, STATES PATENT1-ToFFICE y 2,328,659 FINIsHiNG LINED BRAKE Johnson, Malden, "and AnthonyfArquilla, Medford, Mass.4

Irving n.

SHOE

Appneation January 19, 1940, seria'i No. 314,534 L l,

reclaim. (01. sli-i240',

Our present invention is concerned with abrasively treating, burnishing or nishing lined lbrake shoes, especially the brake shoes. of motor vehicles, by properly conditioning theface of the lined or relinedV shoes .with reference to theparticularbrake assemblyv invvhich they are tcbe incorporated. More particularly the invention aims to! provide va simpliedmethod, with novel .means foruse in the practiceV of suchmethod, whereby the lining applied to brake shoesrnay `be rapidly finished with extreme accuracy. *The Lapparatus of our invention is simple and rugged `in construction, easily adjustablefor shoes O f diierentmakesand sizes, and is substantially `fool-proof in operation. Various other features of improvement both in the method and in the means for Athepurpose stated Will be apparent from the disclosure herein.

Merely by way of further identification of the vield ofour invention, it is noted that typical prior machines of therelatively small class here concerned are represented in the following United -States patents: Simpson 1,906,201; Dodge, 1,918,020; Fisher,` 1,919,545; and Bigelow,

2,118,003.V In various respects our present inventionimproves upon the apparatus and methods oisaidpatents.l In-the drawings illustrating` by Wayof example certain embodiments of our invention and whereby the method thereof may be'practiced:

Fig. 1 is a side elevation of one form of the 'machine a'sawhole; Y- i Fig. 2 is a top plan ofthe machine of Figl';

Fig. 3 isa longitudinal verticalfsection through` `the machine of Figs. land 2, withthemotorand main part of the grinder housing in sideelevation; q

Fig. 4 is a vieW corresponding toa portion of partial vertical cross-section 'as if- "on the line Zia-3a of Fig. 3;"

'Fig. `2, 4with parts in Vhorizontal section and iiiustrating a specimen of the Work, in this instance a-"linedvbrakejshoe, installed in position to be operatedupon;1 .y i i Fig. 4a corresponds toan upper leftportion of Fig. 4, illustrating a method offtreatment of the Fig. 4b is an enlargedsection on the line-ih ilb Fig. 4d is a View similar to Fig. 4a iiiustraung dustrer'n'oval Vanes in association with the abradingwheelyi responding to' Fig; 8.and Fig. 11a Vertical' section taken" longitudinally instead 'of g transversely as in Figg9j,

Fig. 12 illustrates diagrammatically the relative positioning `ofsthe shoe and the rotary abrasive element in accordance with one feature of the invention; andt i;

Figs. 13'and14 show-n a similar manner asin Fig. 12 certain contrasting priorconstructions, 'said Figs;` 12 `to lll'being a related 'diagram'series 'portraying the advantages of applicantsnovel construction as in Fig. 12 as compared Fig.f13`and Fig. 14 constructions. j 1, fi Referring now toA the". drawings' in f more Ide- With said tail, the machine :there shownfor the lpurposes of` illustration is a"compact"mechanical .unit of simplifled'and rugged cnstruc'tion'and attractive"inffappearancer' tfcomprises a stationary lsupporting bed -I,` see particularly Figs. 1, 2,- 5 and l 6, which providesa" base for; thev machine lasv'a whole, adapting the latter"to"be installed for :operation at any convenient location for the Work,

as on a Swork bench or' o'n a suitablezpedestal, frame orj'like 'supporti` rIfhe `bed If is'sh' wn'as an integral casting, open v'at thelbottorri andiofa generalelongated rectangulansh-ape as" viewed in plan. Y'. :Thfrontor forward portion of the bed 11,.' adjacent the operator, mayfbe offset laterally,'Figs. 2, 5 and 6,:to provide `for .a novel offset pesitioningnf the work'reiative tothe axispo the' rotary abrasive element, in the manner fand forthefpurpos'erla'ter tobe described.

-`'I'hebed I hasinc'los'ing side, back and front walls on vvhichjis av ,substantially` horizontal jfloor, in-

cluding a front or Workfsupp'orting portiorrZ and a somewhat lower rear oor portion 3.V Thelfront floor portion 2 constitutes in effect a .tableffor presenting vthe Work tothe abrasive wheel. At

.` its underiace` is a b oss 4 apertured to re ceiveja 'pivotelement' or post 5, The locationof k the lati teronand vrelativelto thebed l` it will bje `noted is constant.,` As fwill, more fullyl appear hereafter,

plan-ir the lateral adjusting this mainpivot position always is the same, irrespective of the size or type of shoe to be nished or the extent to which the lining of' any particular shoe is to beground. 'Said pivot orpost 5 positions the work carrier or work-holding assembly as a whole for lateral swinging movementupon the bed.

Such work unit or carrier herein comprises a two-part base,including` lower andy upper base. plates 6 and 1;' seFigs; 3 and 7. These base plates are complemental similarly shaped elements, as viewed in plan, see Figs. 2, 4 and 8, ofag general part-circular contour inwardlyof their. straight front walls 6a, la. The lower base plate 6 has a substantially central solid section 8- in the nature of a hub; which is vertically apertured tor., K iit the pivot 5. The latter has a heavy flanged circular head 5a seating in alike recess'at the* upper face of the lower base plate E whereby the Work unit as a whole is secured on the bed butV with capacity for; swinging` over'. it about the vertical axis provided by. the pivotpostf 5. .The latter extends below the? boss #ofthe bed and is threaded to receive a nut 5b by which-.thefwork 'carrier 'may be ntightened or loosened. relative to the bed, to adjustthe ease of its swinging movementito.suitxtheparticular operator.v 'f

*Noting particularly` Eig. `3,"the.two partsiand l of the workcarrier'base are arranged for relative transverse adjustment horizontally, to .center or present the arcuate shoe to theabrasive fele.- fment symetrically, regardless of thesize ortype of the particular shoe. lAccordingly thepupper .base'pl'atefl in, theillustrated example is rota.- tively movable relativefto the .under.one, 'about-a fw..-

vertical axis defined by a stud 9 extendingQfreely throughthe upper base plate 'I and'th'reade'd linto the solid portion 8` of the lower'base plate-F.` `f

f Means I is` -herein provided -for` laterally. adjusting, angularly in the present instance', the variably positionable upper memberf'I .ofthecarrier base.' lRefe'rring still to .Egi'S andalso to Figs'. '.8andf9, theilower'base platev 6 vcarriesa crossrod IGrotatably received in and extendingoutwardly .through bearing` apertures, in its.: oppositeaside walls; see particularly Fig.' 9. in which Sand .alsofin `lig. A8...the `portions 'ofzthe zwork+carrier"ass"embly abovel 'the base .members .6:- and :.'I :have been a re;-

lmoved', for clarityin illustration. i Knurled thumb nuts'or .the like I Ixiixedon theendsiof therod l0 afford means for.l turning` thev ,latter to effect; the

relative .lateral adjustment of the two base mem.-

' :bers 6 zand l; from"either side of the machine ,as

may'bemore convenient.

.."-.Theadjusting rod .Illis threaded atY leastlatjits central portion, and there extends through a similarly threaded aperture in 'lanut or traveller I2.

'basev plate 6,"hereiii angularly -or--rotatively',I about fthestud Bras avertical axis.y ,i

Theilwork' carrier. unit has aconvenientrhand grip P or. iever: le.: seenl in .-Figs. 1 to 4- and 6, for

manually' swinging the entire fcarrier `vwith VKthe 'shoe 'mountedthereon across fthe vfaceof the abrasiveielements LvIn the .presentinstance this rklswing-ing` handillever *I 61 is conveniently. lo#

catdlatithe-liront'otithemachine facingith'epp- .3

its

.an axial shaft portion I'I at its inner end.

ward'and retractedfroin lthe-face ofthe abrasive element (to be described); to givea .convenient clearance for inserting V and removing! the.. Ishoe and for feec ling it-.against the abrasivewheel erator, being attached'to and projecting from the frontwall of the under base plate 6.. In Figs. 10 and 11 we have shown a modiii'ed form of means for laterally adjusting the upper member 'I of the carrier base, in which the adjustmentis veffected through the medium of the same hand grip ISA which is engaged by the operator in 'swinging the work.

.Referring tosai'd Figs.10and ll, ,the common handjgripor member I6A,'for swinging the Work Carrier and for laterally adjusting the same, has This shaft yportion extends through and is journaled inthe front wall of the lower base plate 6 and .l also has a bearing in the solid hub portion 8 of "-the lower base platee. On this shaft extension I1 of the hand grip'is fixed a bevel pinion I8 mesh- VYing with a segmental. rack I9 secured as by screws Iiwtothe under face of the upper base plate 1.

Thus by'turning the hand grip ISA on its owny -longitudinalaxisxin one orithezoppositepdireotion vthe upper plate 'Lof 4thecarri'er basewill bejcori.-

respondingly. moved fangul'arlyr relative to; lthe lower base lplate .6; again in, .this.l instance; rotaitively .aboutfthe stud 9 asiarvertical axis, similar;- ly as: described.- i'n .connectionJwith Figs;I 3;'58 and9.vv l. t 1 A z.. .5 i,

Referring again toi Figs. `lio 456. andi''; the work carrier. -unit orl assembly -ffurt'hery eo'mprisesz: an upper. element. or head.'constitutiiigithe. holder proper. .This .headlis'in the torml'of; aitwoepart supporting elementi including; at main-.sputa211r mounted 'on the carrier basei i-ianda `topsplatel Non which tlie work is directlyreceived.`

Said head plate 2li as viewediiniplan. isi-shaped substantially i asseen inA Figs.: 2Y and-4; having-fa general semi-circular contour.: atiiits 'frontpontion and symmetrically narrowing inwardlyithereportion, wl'iereby,` inzpart, 'it i'ssupported flfatvvise Ionthe' upperV plate V:I+-of the Carrierfbalse; f 'L f i The entirehead,` includin'gthelplate members IZtl-and 2li' and .the part's'lcar'r'ied by'them, isnw'v.- .able' lengthwise the machina-upon and-.relaltively tothe carrierfvb'ase Bi-5.41,* for. fee'clirigo'r presenting. `the arcuate'ace of lthe shoegimaibrading contact with the abrasive memberi inithe .course oa nishingoperation-: Accordinglxfthe headplate 2itzha-sfcentrally vdisposed;2141i:its'zllrlflel .l A lface spaced; upright; parallel:guide:E flangesi- V2 3,V .extendingdiametrallygofthe' carrier -piyotj 5,;when f the base plates and I areinregistry-,gasbest 'seen-in Figrl: i Said angesvreeei-ve betweerietliemV acentral llongitudinal gnideib- 24.(on jthe4t0p and 9.

The carrier head.is'adaptedA to beadvanced..

during *,a finishing operationfuitable fmeansis herein provided for. Aso movingthe carrier. head,

26 apertured and threadedto-receiveea screw Vstud .21.

has bearing support in a sleeve 28 at theifrontor 7 f thelower headplatelZQfjand'hasaihandivheel or f' f knob 2t* xed on its projecting endniThefsorewstud' 2l-is-held-.longitudinally,i ,relativa to the portion 29a of said manipulating wheeigaagoiiist i spending flatter arc, will be similarly positioned by. abutment lof. thelan-ges; against .the `innenportionsof? the'` two stops-f2 lb, While :the: smallerrsized; shoes, doWn'tosayf-S ont?" have-.positioning- 'given shoe, by moving the rotary. abrasivel element relative toy the'. fixed.; axis of.' svving...and setting it at the predetermined-radial distance from thelatter appropriate forrfthat shoe,.- asiWill later be more fully. described..

, VWe emphasize here, however,v thatishoe posi.- .tioning meansi of. the simplicity and` easeoii manipulation suchas-.hadzwith the disclosed-,con-r struction, universally applicable toA the. .various shoe sizes, ,isz largely possible only because' the axis of-swingfforrtheshoe is constantandf'the radius of .finish isiset Iby adjusting the. abrasive wheelk toward and fromV that axis fandthenifeedingand swinginar theshoe: against theiwheel;

Otherwise; if' the axis tof `swingwere Ato be shifted,

for exampleas in the machineiof; thefiBigeloW patent referred. to, some. .complicated 'and pro. 4p ortionate adjustment for. practically everydiflfer-` ent .shoe wouldbenecessary, dile to-the different curvature and resulting. slightly. dii-erent-1inward projection of the different: shoes relative: to .our universal holding device,l ifja minimum .andiunis form thickness.. of LtheV liningis .to be yremeveolin each case. other.` words, in.accordance-. with our. invention, the .distance from .ther axisof swing 5.'.to the outer face -of the shoe before .lg-rinding, .also the; relation ofthe centersof.l theshoe itself to the axis of swingglare immaterial,'.to.the{ex:

ltent;..indicated,andare notare'lied on.inlrneasur-l ing andisettingthemachine for the-desiredrradius for;v thenisliedtface of ythe shoec.: Instead, `the grinding wheel is setftooperate ina planespaoed from lthe xed axis of swingzby.exactlythameasurement; desiredffor.r the. .radius of? the. 'iinifshed shoe,;namely,ithe radiusfof its drum-.r Ifalrshoe forca -dr.um.;one'inch `'greater or one-inch." les'sfin radiusnis*tog-beinished, then thev wheeliiseset back :fromiforf-a'dvanced toward the fixed. axigf swing-:byexactlyone inch, andanot.isome't propor- .tionatelygV reduced oraugmentedr distance; lessfror greater: than... one inch in: order. to compensate fo-r the` c iierentfk degree of'. curvature.V` and. .com

' it-rolzproectionfof thedarger or smaller. shoe'.1,

f.- .In'..,placr1gafshoeniny the..machine-. the. .operato r .merelyei-,s i1-f approximately centrally .onsy the holder plate, laying the radial shoe. webgiwf-.iiat .wiseg onl thev yinnerendv .f oi,k they lditerzand lrmly abutting; the vvertical vshoevilange* AFf,-aga-nst. the stop elements v2| b. yAccuratef1centering..ofi Lthe shoe; laterally ofthe holder; isgsu'bsequentlmhad, by turning oneer: thez other tof.: the lateral .fade

vjusting knobsor buttons I l rpreviouslyftdescribed-f,

.or-.fin the construction o.f.l1? `i gs. Jlandc-ll bw-axially rotating. .the hand-ler! 6,. wherelevafthe..ilrner .late laof Athe Qarrierkbaseiandsai-1ffnartsraboveiitaare bodily adjusted.' horizontallyjrelative toxthefpiy-y ota'lly xedsunderbasecplatezf: ,i y: Afs'` best .iseenin Figs.. 3,".41andi4a; :theLshoe-:posi-l tioninglabutments .2Mb of the holderplatezdesirably also are formed at their flange-engaging portionsv with. a .recess 2 Ic, at. the. upper corner regions, .;in,the. vicinityr of thejuncture o f..-.the radial-web W oranshoe-with itszperpendicular arcuatefange This recessedform-ation ancona,r

moda-tesethe qreenforcingenlargement, o r.- 'possibile irregular projections sometimes .'p-resentfat that partof a shoe, as indicated. at wr in Fig. 4b.

No. 1,764,847, aformer Chryslery shoe. T o-.a-

cominodate. such. now unusual vformations the holderA plate .2l .may be .appropriatelyfrecessed at its-upperlfacefas indicated inV dottedzline-at 21d inllfig. 1321 Forthe rarecaseoi a'shoe web coni struction not thus accommodated.. the holder plate 2|, being readily removable, may be replaced". by. 1a like plate specially. formed ,for the purpose, .Or an adapter-block conforming` tothe particular special shoe webmay beset flatwise on the holder plate of'the present figures.v

The/shoe' to ble nished is'securely. held inthe described v,operative vposition'on the holcler'plate l v Zljofthecarrier head, by meansof an easily applie'dholddown or clamping. device, Figs.. l to 4,; 6 and-"7. Said means herecomprisesaunit'ary. clnipfll" in tlie forni of'a spiden or.. yoke. It inludesja Amain 4cri body portion vertically vslotted forjthe'passage'- of Van upright stud.. .45 .anchored on-the^`hoide`r pia-te' 2l.' At. its inner lend the clamp'hasa' pair' of divergent jand'downwardly projecting` feet 118k adapted to engage theA upper, facer of itheradial web W of a positioned shoe,

preferably" adjacent the' corresporndi'n-gv position.-

Vingf'stopsl bici-the holderj plate. `The clamp 44,

previously described andA downturned ,at^"the'1 outeren'ds'tol standj'i'ilatwise .on theA tp.` faceof'. the; holderplateil'." ff l Byturning down a `clamp nut49 .onithe threadl ed'uppereiid off th'estud '45,.th'e .clamp is .-forced down ontol the rsh'oe' web and." the .holder vplate.k Thus thegushoe is rmly clamped. and 'held Ain. operativeposition;'iromwhich itfrnay be quickly, 4released vIoncompletion of ai finishing "operation, merelyrbyrloosening said' nut 49." '48"fsurrounding Vthe rs'tu d:45"bfelow automaticailyf'liits the inner ,shoe-engaging. end ofJ the clamp' asthe nut "49 is back'ed. off, .thus ,in eiect'automatically opening the jaw o'f theclamp andv facilitating ythe insertion .and removal of they shoes,` whilej "also 'guiding theiolamp. andholding it against undesireddisplacementrelative tothe otherv parts when no shoe is in position.,

YThe mechanism thus far described. comprises. the'yvork positioning.and. manipulating means; wherebyfhearcuate vlined shoes are. presented.

fort'horizfont'al" swinging about 'the V fixed .aXisf 5 .on .the machine bedl. Weturn nowto the abrading,..or grinding ,.assembly, includingthe motor-A driven. grlinder. wheelorabrasive .element together..V Withthe means whereby in'cooperation with said fixedpvot. 5.-. thradius tofwhich the shoe ,is .to .b c groun 'd;.isaccurately.predetermined and.-set

A coi1'.spring the clamp .44

theparticular shoe` is '.intended. In accordance withour inventionfthis setting oftheradius of grind, that is, the .radius forthe nished outerv by screws to a hub 53 fast onthe shaft 54 of the electric motor 55. The vmotor 55 is-demountably secured on abase or sliderEG mounted on the rear portion ofthe machine-bed l and movable Aforwardly'and rearwardly thereon.` The slide is guided for said movement by a slotted way 51 in thetop wall of the bed l.

vThe abrasive element i! has a housing comprisingV a back plate attached to said base slide 58 as by the bolts'a, Figs..2land'3, and a detachable flanged front or cover plate 59 secured to the backplate. 58 `as by the series of screws around their edge portions, `as seen` inA Figs. 6

\ The illustratedfmachine is constructed and arranged for rotation of the abrasive wheely 50 in the counter-clockwise direction, looking from the front of the Imachinetoward the Working face of the wheel 5b, as in said Figs. 6 and 7. The work dust is collected in the wheel housing and is driven or carried on', herein at thebase of the housing. The latterfaccordingly is formed with a dust discharge'outlet El), at its right side, again as viewed in Figs. 6 and 7, in position to receive the dust from` the counter-clockwise rotating wheel. As will be more fully explained, the action of the wheel itself, due largelytothe relative position of the shoe and wheel, is adequate to expel the dust without theY aid of blower or suc tion means. Y 1- i;

The front or cover plate 59 of the housingis `apertured at 6I, Figs. 3, 4,'6 and '7,opposite the shoe` position, for presenting the larcuate lined face of the shoeto the wheel 50 and for swinging it across the latter about-the fixed axis 5 ofy the carrier. region of contact of the shoe` withthe abrasive wheel 50 is laterallyV oifset'from the wheel axis. In other words, the axisof vswing` for the shoe, as defined by the fixedpivot 5, is to one side, herein to the' left, of the vertical planethrough the wheel axis.` Further,Vv the work carrier4` and holding means` are so constructed `and arranged relative to the grinder unit `that the horizontal plane of a supported shoeis" vertically oiset with respect to the horizontal plane'through the wheel/axis. l In the illustrated instancethe shoe is presented to `the wheel belowV the horizontal axis of the latter, substantially midway vertically' ItA is here particularly noted that `the -be more fuiiylpoirite'd out in connection `with the diagrammatic `FigsLlZ to 14:4 l..." l

The supporting base or slide 561 for the rotary grinder unit is in the form ofan inverted hollow block or plate with supporting side Walls 56a, 56a received on the `machine bed I; see particularly Fig.` 3a. Itsrear Wall has a depending guide foot 63 slidably received in the slot 51 lof the bed l while at its `front portion isia further guiding element or leg 64 extending down through saidf'slo't 51 and providing the connection between 'the lgrinderunit base andthe meansfor slidablyl movingit-l along the bed.v I. I Said means Vincludes `a .longitudinal screw: shaft 65hou`sed in the 'bed 4and extending through a threaded aperture at the lower end Iof said 'connecting grinder leg 64. Y

By turning this screwshaft 65 in one or ythe opposite direction -the'rota'ry abrasive unit as`a Whole is .proportionately advanced or retracted `relative'to the xed axis of swing-.ofthe work carrier, for initially 'setting' the radius the particular shoe is to be finished.

t0 `vhh ySaid abrasive unit including its base t'gniotor v55 and enclosed Wheel 53 is yieldablyheld down on the machine bed by means'such Aasbest seen v Vin Figs. l3 and 3a. For this purpose We havepro.-

vided a pair of rollers 66 rotatableon across shaft 61 so as to krun on and bear yieldably up againstthe under face of the horizontal top wall `3 Vof the machine bed VI ,one roller 66 at eachside of the guide slot 51. l Theroller shaft El is vertically movably heldbetween the leg 64 andthe forked` lower end of a springplate 68 screwed -ojr otherwise. secured to -the upper portioriVof` said leg 84. It is `vertically supportedby a coil spring Si) having its lower end anchored "in the `roller :shaft-I and fastened at its upper endto a pin 'ill shoe.

held ina pair of ears 'Il at the upper-portion of said plate. The tension of the spring 'ESjis made sufficient to keep themotor andabra'sive wheel unit at all times rmly but yieldablyseated on the machine bed "l, while `freely permitting them to be vadjusted along it to a setting to afford the proper iinished radius for any'given The adjusting screwv -shaft l has"V al nonthreaded frontend-portion 65a extending loosely througha sleeve 'F3 set in an opening in theiront wall ofthe machine bed `l and xed toI the latter, sadsleeve'carrying a ball thrust bearing l'lrotatably supporting the serewshaft' withca- .pacity for bodily movement-'faxing at the `will of betweenvthe level of the `whe'elaxis and the bottom edgeof the wheel. Thus 'the wheel and the shoe are so relatively disposed that the `zoneof abrading'conta'ct with the shoe is upon a 45 radiusv of the wheel, .that is, approximatelymidway between its horizontal andthe vertical diamfeters. -In the machine shown this radial position is that vsubstantially halff-way between the 6 oclock and 9 oclock positions on the wheel, as

viewed in Figs. 6 andl'Lor inother words along the central radius of its lower leftquadrant. The purpose and advantages of thisconstruction will the operator, fora purpose to be Vdescribed;` This screwshaftfl is yieldably heldin its normal rear position asfseen in Fig.`3 by meansof astro'hg surrounding coil springv 'i5 bearing between vcollars 'mand 'Il on the shaft 65. Atits rea-r end it has an abutment'element'l shown as aseparatedisk or plate xed on the `shaft 65 las lbya nut 18a,said relement 'I8 `norr'nally taking against the Iface of one part of a ball thrust" bearing i9 at the inner end of a supporting block or hanger 80. The outer end Elfof the latter isofreduc'd diameter and is threaded through anexternaluly normaldor zero position ofthe screwshaft 65- whenever desired,rfor example to compensate for vwear at the face of thabrading disk 50.

Itis Vdesirable in finishing a brake shoe to skive `or chamfer the lining at` its ends,beve`ling them fvided with hand llevers :19.11. -Sl is. .then

- a wink handle .frfcr ra.

:rapidg'and -positvegskiving action. @It is-zforrthis f -purposenthat the :adjusting screw-.shaft ofrzthe grinder. wheel .unit 1 is constructed-fand arranged .ingthfeidescribed manner. with-fcapacityrfor.-bodily cuniierstoodf '.efectsya:corresponding@ movement of ftheigrinder unit: to skiverthe shoe rends.

rMeans- ,quickly and f conveniently available 'to .fthegoperatoriis .provided forso movingagthe screw rshaftal and theffgrinder. unity .with it,v rforwardly,

tt-1ere; is;v adjustably vthreaded.:,onjthe screw: shaft 55y an.; abutment nutv g-and an .associated ilock .zzmit 85a.; Behindeand in.; camm-ing -:engagement =twth';tlle abutrnenty nutrf isf a; pair ,of cam A.Ln-

justablyfixed; :as'zby zset. screw; 813.10m a: transverse -yrokshat i159 .ioilrnaledi in the: sidez wallsof the fmachinegloed @and `.proj ecting outwardly f through ytl'iem.Y Atreachf proj acting end; of c thisf rock shaft sxisfanfoperating,-leveriellyand 9|'. The'se extend forwardly; alongcand in general conformitylwith gthegsidesv .of thee machine ibase .I and i have ,r colilflTS :9L andi respectively iat; their rear. ends: for :fix-ingV them .allponffthe corresponding :ends lof. the .rock shaft ,1119. -ffAt "their, outer ,or front. ends the f operating-Lleversrf and v9.1 gare respectively pro- 'psl14;and;- 955,; one convenient- :lyyaccessibleto th ,operator,atfeithensideof the Ina-china irrespectiyefof thezoperators position aridi-permitting :him ftp use either hand yhe .f may fprefer..4 Ir desiredfotheror supplemental controly Tfor.thefskiyingfoperation may he provided, and inzthisfconnectionzitewll; b e v,understcmot.that the .terms 5m-anual or-handswith reference tothe '.slriving :control means, illustrateddoy'zthe :operatinge levers 510, r9 l, arepused iin; theirkbroad. sense .to nludeam formoractuationrhy Grat the Y,willfof tlieoperator; whether the .operating part is engagedby his hand or is votherwise operated l ley him or. at his election ,It willy be, understood :from z the foregoing that inorder to skivethe shoedizningeends, either-.-be foreor afterrnishing thermainrfaceof the; shoe, ,the handle-l l-li or the shoe ycarriage-:is `*nrO'veLd to oneside or theother, swinging thefshoe Vsofas to f, position 1 one end :opposite the .abrasive .wheeli. The handle-l of one ,o1-the` .other ,of the. loperating n .epressed .for `the r brief period f-reqlliledgto 'iorcefandshcldfthe. wheel :.50 .against the shoe` end gsuiciently tto. fafford the zbevelgs-rindfIt wllihernoteid thatthefoperating ulvera9,0.ar1d19l arefQfr-sabstantial;lengthamuch greater than =1thatof the zcarrningersi; afrhusa smwverullevraeeiszaiordedrnecessitating `but a .f comnaratvelrfslieht: dorm-:presenteren a never 1 lkaldlex 4, .0 ndcthljough raf-short .distance {only,in-order h' tthe ascrew; sli-aft: iand. its

.cpnnected,-grirrder iinitgforwardly': inthe-manner 81 :carries .fannicltometer settingscale fherein amandine-...Cananea around the dia1;;.wheel 9.1.

'equal ."units. tionarylpointer or f index lill] mounted-.ena :con-

aTheEgraduation units: may :bezet-:any desiredgnev.ness lof ispacing'ffor..examplerfrom D to e200 lzin This A-soalefisv read. opposite .a ista- Vvenientizixed part; herein theashaftsleeve 1.3.

yIn setting Ythe machine. 'foranyg givemsizeaof :shoe within its capacityggtheabrasiveaunit in'-l cluding the Wheel iszmovedatoithe.properilo cation `on the lied.; l'rto .give:rthe;desire'd 4radius .of igrind, .that is, torspace f. the r Workinggface :ofy

.the'wheel Eri) `at azdistance "from thexedzaaxis `5 ofthe carrier unit-equalto .the radiusroffthe brake druinifor that-shoe,v including', any :devia-- tion from standard' foundin: the-particular drum. .The standard drum'zsizes, in diameters,.rnayzbe 1.determined"from: schedules availablefto the op:- `erator. `But in) the 'rcase 4of a-drumwhich;has .seen considerable.y service, .orf preferably in f any case, :the internal-.diameter :of 1the;drmn'will';=b.e

determined by actual measurement.`v

Referring to Figs. 1l and 2;::the lsliding'fbase 5.6, ofithe ,abrasive unitzhasuab onef'side, herein the left, agpointe'r or; index F l l(13 :cooperating with an indexfmemberfll upon the'z'machine bed I. This member l 04. vcarries on itsitop, faceY afscale M25 r facing upwardly and fhencegeasily; read; from the operatorsusualplacefat thefrontfof the' ma:- chine. If desired the scale graduations may ,fa-lso be applied :at the adjacent'verticalzface ofithe indexmember |534,rasatfll!5zr',.inrig.'1.`

said Scale ,los vis ,calibratedwo read k;.direeuy' .Whileithat; is a. simple calculation.. mistakesxare .less likely. ifthe I nel-:fdsfor'` itjis. eliminated;

As illustrated in Figs. 1 and 2 theabrasive wWheel.ilaiarroritsy slideare -set-f:or*a;'shoe ofex- Having :determined fof-its micrometer; scalevl; accurately; oppositezth pointerflgll, o

, This dialjscale-99 isjmade'tozreadgdirectlytin thousandths ,ofY an inch o f I drum. diameter 'measurement, again avoidingenecessitylfor any-mental calculation. on thev operatorspart. The circum-r ference of thedial wheel of'the'illustrated embodiment hastwenty main units or idivisions,

itsdial199, say-from 0-to 10,1.varies the grinder setting through .OlOofan inch ordrum diameter measurement, yactually movinggthe ,grinder slide complete dial wheel turn hence is arrangedto.

give a travel of twenty times .005 ofY anY inch `or .100 of an inch for the grinderslide. Thus five turns of the dialy wheel and its shaft 65 produce a traversing movement of '.500 of an inch (one-half inch), corresponding to a? drum diameter measurement of 'one inch', and correspond-v ing alsoito. one unit upon the main scale 105;.

In other words, the slidepointer. HB3 ismoved on its scale HB5 through one main graduation, say from the 9inch mark to the 10inch mark, in ve turns of the crank handle 498. The screw shaft 65 is threaded accordingly, providing it with a .l-inch'lead. Again, iivecornplete turns i of the dial micrometer scale 99 are `equal to one graduation of the main scale vl 05, and hence each of the twenty units of `the micrometer scale 99gis equal to one-twentieth of one-fth of a main scale graduation, that is,one one-,hundredthof the latter or .0110 ofan inch o f'drum diameter movement, but giving `an actual movementof I Vmain?` operating handleA Iiabout its longitudinal tered transversely ofthe machine, Vso as to bring its medial radius into accurate parallelism with the. axisof the abrasivewheel when the carrier is in its central position, as shown in Figs. 2 and 4. `This is readily'done by manipulation of either of thecentering knobs Il` of'Figs. 1 to 9 or in the embodiment ofY Figs." 10 `to 11 by rotating the axis. v Y

` In the operation of finishing a shoe, thelatter isswungtofand fro across andin contact with the face `of therotating `abrasive wheel, by manually moving the operating handle. I6 back and forthzfrom-one side tothe other.` As the operation progresses .the "shoe is fed toward the wheel asneeded to maintain contact witheit, .by turnthe grinder slide of one-half that amount .or

drum should be increased by 4one-half the oversize diametral measurement of the drum, .090ofA All that the uopaninch in the assumed case. Y erator need dois to set Ythe slide pointer ID3 at 12 on themain scale ,|05 and then Vturn the dial wheel 91 toward the left,'Fg. 2, tobring theV graduation 180 opposite the pointer Ilm. The

setting of the wheel face is thereby actuallyv increased but .090 of aninch, automaticallyv po# sitioning it exactly 6.090 inches fromthev` axis 5, in accurate conformity tothe 12-.180-inchhdiameter of the drum. `Thus any fractional-inch drum-sizes or variations above or below standard are readily taken care of by the micrometer dial 97, reading it directly in gureso the determined drurn diameter. Fractions above .200 of an inch are set by giving the` dial `one orV more additional turns as needed. In that connection the dial marks may carry one or more additional series of numbers as 2|@ to 39B, etc.;` see Fig. 4c. Also if desired, the dial, scale 99 may `be num.- beredto read from zero in the opposite direction around the wheel, for `settingfclearance-s or un-f dersizes by measuring down from a given size,

but in practice it is found preferable to lmake the setting additively, as say 1l inches plus .750 rather than as 12 inches minusl).

Having now set the abrasive' wheel to the correct radial distance from the Vswing axis 5 corre-v sponding lto the. given drum diameter, the shoe is placed with its web latwise on the holder plate 2 I, in approximately central position and its then vertical ange isY abutted against the positioning stops 2lb. The shoe is secured merely by turn'- ing down the nut d@ of the clamp Mi. It will be understood that the holder head Ztl-2l has rst been moved toward the front of the machine to any extentneeded to admit the shoe, by turning the feed knob 29, either before orafter setting the abrasive unitas above described. Ob-

viously any convenient order may be followed in setting thev abrasive wheel, adjusting the holder` head, and insertingthe shoe. At any time after clamping the shoe fit may be accurately cenl `rotating disk. "This remains :true irrespective of ing the feed screw` 29h *The abrasive action is continued until-the desired thickness of `material has been removed-generally buta small fraction' of an inch. YThe Iabrading, grinding, burni'shingv or wfinishing is complete 'when' `it is noted that the shoe lining' `barely contacts or just clears the abrasive rdisk!) uniformly throughout an entire swingfrom end to end, no more material being removed. The entirearea of the lined face of the shoe` then lies upon a true arc centered at the fiXed'aXis 5 of the carrier assembly,.correspond ing to the center'of the brake drum. V:

The ends of the lining may then be skived, as previously explainedyby bringing them successively opposite the working areaof the wheel and manually depressing cneor-the` other of-the chamfering leversl 94, ,95;` If preferred this chamferingmay `be done before the intermediate i s bodyportion ofthe shoe is-i'ln'ished.' i l .'It will be noted as an important feature of our invention that oncethe machine has been-set for-the given drum size, there is no subsequent variatiorrinl the position of the axis. about which theshoe is swungacross the working face of the any infeeding` of the shoe.. And since` this axis of swing `is fixed, the carriage pivot 5 beingnonlvariably positioned on the fbed |,there is no way for this controlling'point to be disturbed either 'in setting up the machine'for a given job orl in performing the, Work. .The important deter# mination of the distance "of the face of the abrading `element `from the axis on which the shoe swings is made-wholly independently of the work carrier and of any particular setting of any of its parts. 1 Asa further. result the entire struc--v ture ofV the carrier'is 'simplified Aand so can be madeimorerugged'than otherwise. This construction ,and yarrangement.contrasts with one in which Vthepivot about which `the work is'. to be swung is itself adjustable. lThere the swinging of the work and its holding mechanism in the course of a job tends to throw the main pivot out of accurate setting.\Any such'tendency is avoided in accordance* with our invention, to` gether withV the numerous other advantages noted, through the mediumrof permanently fixing the work-swinging axis and adjustably movingthe abrasive unit toward or` from it, inde-.- pendently of the work carriage and any other parts. a.

Among further advantages of the illustrated construction we note that our holder head, com prising the main parts 20 and 2l, is supported on a longitudinally .immovable base portion or elementli,` 1 of the carriage assembly.V Hence its feeding movement isi accurately controllable with more certainty "thanif thislhe'ad were mounted on an element whichv in' turnmust be. slidable inithe 2sam'elongitiidinaldirection. Such @lon gis tudinally immovable .construction c-for. .the Dbase portion of "the f carriage 'is 1p ossible f'becausethereis= :no mechanicalzgoperating Aconnection between ourfcarria'ge .andfthe svvin'geradius settingrm'eans, the .abrasive unit 'itself being?` shifted zforthe radiusesetting purposes ratherthan anyy .partei theicarriage. .For'similar reasonsvnolspecialfprooperating results is Hthe '.faet thatnthe' longitu-I dinally Ffeedable 'holder head-` is fabove "th'erixed axialelernent i andstructurallys'eparate from it, solthat ithelhorizont'al f-planef-io'f contact lof "the holder head with the i surface; on lzwhich it. isflongit'udi'nally adjustablanamelythe top. face ofthe upperbase member .1, .is different 'frornandverticallyf-spaced 'ab'ove the 'horizontal 'planular surface "over 'which c the work-swinging movement of Y the 'carrierfas a whole .takes place, namelyithe topface ofthe front vtable vportion 'Z'.ofthe'machine bed'litself. It `:is'alsohnotableth'at the centerlandraxistgfor the'lateral centering adjustment of thefshoe fis. separate. from and wholly independentfof theixed axial-member 5` rfor'. the vshoe-swinging movement, so thatin making.' such lateralv adjustmentthere 'is no likelihoo'd of disturbing theirelationv "between "said swingiaxis and the abrasive disk-50. 1 j

` Referring .again'to the 'shoefend -lskiving means, the resulting bevel-by? a given thro'W'of the chamfering levers 94, 95'may` befadjusted inv depthto ysuit;theparticularlining-material, type of brake or other .circum'stance'; ,As seen'in Figs. Band 5', .the nut '85 'engaged ibytthencamiingers to effect the quick vforward chamfering movement of theabrasive unit may bei shifted-on theiscrew shaftl" toward `or from .`the"normal'position kof the *cam fingers illustrated. A correspondingly f greater or less advance of the abrasive unit re-v sults', for'the same given .angular movement of thefinger-car'rying.rock shaft' 89. The'throw of the chamfering'levers,.if desired, may be'adjustably or variably limited by. anysuitable means, not necessary toshow" in itheidrawings.

The mechanism for setting" the 'abrasive unit, already described, "has-as' an important feature thecap'a'citytto incorporate ia constant'plus or minus factor in they setting'of *the micrometer dialvS'T, to compensate for'anyparticular condition' requiring correction, such 'for :example as wear of theworkingtface of-'the abrasive diskV 50". Wherf'so `employed the zero reading ofthe micrometer scale`99, instead of indicating a position-of the grinderactually at saylG inches from thelaxis 5v givesa radiuslsetting of-perhaps'6-040 orf5.960 inches. To takevvaspecic instance; it is Vfound' that the face of the abrasive disk 550 hais been worn to the'deptho'f 0.050'ofv an inch, so'that itis that much further-from'thecarriage axis 5 than previously, at-'anyparticular'intended setting. To correct'for this'a constant minus factor of 0.050 is needed; that is, the zero position 2,32 egeiso ,inch ,-Henc'e the correction of Y01050 o'fan'inchin the'assumed instance involves a distance correspondingto one-half 'turn ofathe shaft,v in this case inthe directionto advance the grinder slide. rlhis grinder .unit Zero positionadjustment, in the construction here shown by ,wayI ofexample, is'made without disturbing 'the fixed-position of the dial Wheel S'I'onand relative to the 'screw shaft 655 As best seen 1in Fig. 3, at its lowerright corner'portion, and also in Fig. l, said dial Wheel' l Y Returning to the vabove example in which Wer assume that a minus factor of 0.050 of aninch is desired, `andreferring now particularlyto'Figs. l' and 3,'the'lock nut 84 on vthe rearendlaof the threaded portionl of the hanger or bearing block 80 is loosened. Said vblock as a whole,'in' cluding'its threaded stem portions SIL-81a," is then turned vrelative 'to its supporting collar 82-83 in a clockwise direction facing the rear ofthe machine, that is, asllookin'g from' the left inFig.' 3': Said hanger block thus is moved'bod= il-yforwa'rd,r toward the right 'in said figure. Since it abuts the end of'thescrew shaft 65, the latter andthe entirev grinder slide assembly are correspondingly advanced. Graduation mark-- ingslindicating the extent of such longitudinal adjustment of the grinder slide assembly per givof 'the'scaleSS lis made tto give'what previously en'degr'ee o'f turn ofthe blockii may be provided, ifdesire`d,'at any convenient adjacent'location. The threadv on the stem l8| of the block is selected to give thefne increments of adjustment' desired axially, carrying the grinder unit as a Whole with it. The face of the abrasive Wheel 50 accordingly assumes its desired 'corrected position, and the Zero position of the dial remains unchanged rela.- tive to the index pointer 00. Obviously the corf rective factor thus introduced need not. correspond-to Vany particularfraction or multiple of the dial scale' 9, being applied entirely inde-y pendently of the latter, in the manner described.

Axial movement of the shaft ,65 as well as rotation thereof is facilitated by its previously described bearings 74, '19, with avoidance of excessive Wear, it being' understood that the compression return spring 'l5 surrounding the shaft'65 exerts substantial pressure, adequate to insure and yieldably but' firmly tohold it at its par'-` ticular setting during a' grinding operation. ...This

return movement is limited andthe j :nartszprop-k erly repositioned, as previously explained, by return engagement of the rear' end of theshaft -65 and its abutment element 'l0 with the adjustable positioning and bearing block Eil. The provision of :such adjustable member 8?, it Will be seen, permits of corrective adjustment in the positioning of `the abrasive unit slide assembly` inthe manner described, whether, the 'need thereforis due tov/ear at'theface of theabrading wheel. or. is otherwise occasioned.

In connection with. any such adjustment the abutment nut .851 engaged by the cam nngers 86 ot the chazmfering: mechanism may be correspondinglyresetonthescrew shaft -65 so that the depth: of. bevel given. the: shoe ends will be the' same as before said; adjustment, for the same given'` movement of'qtliev chamferinglevers 9D; 9|.

At an earlier: point inthe specification we have pointed' outfthat the shoes are novelly presented to:the;grinder'disk insuch manner that the area off abrading-actionfisacentered'upon a 45 radius off the disk', the medial radiusof the lower left quadrant in the illustrated embodiment. The purpose andfresulting advantages in this connectionwill bemorereadily understood; from the diagrammatic views, Figs. 12; 13 and 14.

Referring tosaid diagrams, Fig. 1-2 represents the construction and arrangement of our inventiorr asglirr theillustrated machine.` A major por-v tion of` the abrasive disk 5@ is; shown, its axial center'vbeing, indicated. atV (7J-54; the numeral referring: to theshaft 5,49 of the grinder motor. Thehorizontal' and vertical diameterlines of the disk. area shown--bygthe broken `lines h-h and u-v; The-outer` convex face oi a shoe positioned inthe machine is indicated by the wide dash-line rectangle marked S.` Thework carriage is assumedto=` be midway in its swing, 'so that its centra-l vertical area or` band is at the moment abrasive contact with the disk 5t. This contact. band` isz represented.l by the smaller central dotted-line hatched rectangle Z.

The medial or 45 radius of the lower left quad-A rant; of the grinder, disk 5.0 is indicated by the heavier radial linemarked 45. As previously described, theconstruction-ot the swinging carniage andthe'work holder, and also that of the abrasive lunit and the machine bed' in itsV entirety, is madel such that the. areal center CP ot the abrasive, contact band Z of the shoe S standsoppositesaid 45 radius, at a` point along the latter desi-rably atleast approximately mid-- way from thedsk axis C-54 .toward the outer edge of the disk.

Referring stillY to Fig, 12, thereare also shown those radii whichfpassthrough. the points or corners ofthe contact band- Z that are the farthest spaced in the direction circumferentially of the disk. .These radii determine a central angle e. Y

Said. Fig. 12 furtherv includes a series of four concentric arcs, eachdescribed about the disk center.(Lt-Elli These arcuate'lines represent the paths described by the abrasive particles of the Wheel 5U at the several radial distances from` the disk axis indicated. It will be noted that the outermost and the innermost of the four arcs pass through those points or corners of the band Z which arethemost remote from and the nearest to the disk center, respectively. They define between themran arcuate path or Zone R, of a width represented by the longer double-headed arrow. The intermediatepair of arcs represent Ythe paths of thegabrasive particles which cross the indicated 45 radiusat the average distance (half-way) between the areal center point CP of the band Z and the respective outer and inner bonzlers of the total zone R. These intermediate arcs ydene between them an arcuate path or zone RA, ofthe widthcorresponding to the shorter double-headed arrow. Saidnarrower `zone RA accordingly represents the average or centraLwork-productive half-.width of the total abrasive zone R. In other Words, zone R comprehends every point and particle on the face of the disk 5i!` which has any contactl whatsoever with the shoe, regardlessrof the extent of that contact; and sub-zone RA of zone R is what weshall term the major effective zone of abrasive contact of the shoe and wheel. As stated, its arcuate sides are determinedby measuring from the areal center CP along the central radiusthe 45. radius in Fig. 12-one-half the distance toward =`each of the vertical sides of the contact bandZ, at the opposite sides respectively of said areal center CP.

That portion of the total contactr band Z which is crossed bysaid major eiective zone RA is stipled and separately designated as ZA. This stipled area will be termedthe major-eiective contact area.

In eachof Figs. 13 and 14 the same elements, angles, radii and zonesV are drawn, in connection with the; same contact band Z upon the shoe S, the corresponding features having the same reference characters as in Fig'. l2. Said Figs. 13 and 14 are included for the purpose of contrast with the Fig. 12` construction of our invention,`

wherein the Contact band Z is `centered "upon the 45 radius. Fig. -13 shows Ithe band Z, of precisely the. same vertical` and horizontal dimensions upon the sameshoe S' as inFig. 12, but with the shoe and grinder disk 5i)` Vrelatively positioned to `locate the areal center CP of band Z` centially` upon, theA horizontal diameter line h-t of the disk. The same applies also to Fig. 14, wherein the areal center CP of the same band Z is centrally disposed upon the verticall diameter line'Ur-v of the disk 50. i

'From an inspection of Fig. 12 and a comparisonthereofwith each of Figs. 13 and 14 `it will be, apparent that in accordance with ourconstruction as diagrammed in Fig.'12 the eiiiciency and economy of the abradingaction are materially augmented, among other new and benecial results to be referred to. In general, any favorable factors of the yhorizontal positioning of Fig. 13 and of the ver-tical positioning of Fig. 14 arey all` ycombined and availed of compositely, with Aa total result largely superior to that ob,` tainable from either of the Fig. 13 or Fig. 14

arrangements. l

Let us'consider for example `the comparative radial extents or widths of the total abrasive zones R in the three diagrams. It is immediately obvious that our Fig. 12 constructionV provides a total abrasive zone R of the greatest width, noting particularly the length of the double-headed arrow R near the top of each diagram. IThe vertical construction of Fig. 14 is second in this respect, andthe horizontaliconstruction of Fig. 13 is the most unfavorable, its double-headed arrow 4R being considerably the shortest. The signiicanceof this is that in our construction the work ofk grinding a givenarea at the face of a shoe is `distributed over an importantlyl greater area of the abrasive disk, so thatmore of the abrading material of the disk is availed of in the given job, and any one zone or any one particle at the wheel face is called on to ololess `workfor the same resulting grind. The life of the abrading disk accordingly is extended proportionately.

Now let us compare the gures with respect to their several major `effective contact areas ZA.

'The benefits here, with our Fig. 12 construction,

are perhaps of even greater `impor-tance than those Just noted in connection with the total abrasive zones R. This area ZA, represented by the stipled portion in each of the diagrams, may perhaps best be understood as that area over which the grinding is performed at the average lineal speed, that is, the average of all the lineal speeds of all the particles which take part in the grinding action to any extent whatsoever, including the` slowest lineally moving particle, namely the one nearest the disk center C54, andV also the most rapidly lineally moving parti-` cle, namely the one most remote from the disk center C-Ell. The abrasive wheel 50 is assumed to have the same rotary speed in each of the diagrams. This stipled area ZA may otherwise be termed the area of average uniform lineal speed 0f grind.

It is an accepted fact that a more uniform and otherwise better grinding action results where all of Va surface to be ground is acted upon at the same lineal speed over the entire contacted part i of the abrading element. For this reason the nat face o f a wheel is not considered to be appropriate to some types of abrading work. But inaccordance with our invention face grinding "is adaptedto the finishing of brake shoes with superior results over those heretofore obtained in such manner, because a substantially greater portion ofv the total grinding effort is brought within the major effective area or average uniform speed of grind area ZA.

Said average effective area ZA of our Fig. 12 construction is almost twice that of Fig. 13 or of Fig. 14, as is clear from mere inspection of the diagrams.

In the horizontal type of Fig. 13 the maximum lineal speed variation in the abrading contact, between the inner and outer arcuate edges of the area ZA, is the least, as indicated bythe relatively shortarro-w RA in said figure.V Such total speed variation is somewhat more in the vertical type of Fig. 14, as indicated by its arrow RA. In our Fig. 12 construction it is substantially the same a'sfor Fig. 14, the arrowsy RA of Fig. 12 and off'Fig. 14 being about of a length. But this maximum lineal speed variation within the confines of the major effective areas ZA is not great'- ly different in any one of the three instances. The three arrows RA have a length relation in the ratio of about 18, 17 and 12 for Figs. 12, 14 and 13 respectively. Hence obviously there is no substantial disadvantage in the Fig. 12 construction in this respect of total speed variation, certainly nothing to Vneutralize to any practical extent its great advantage in the approximate doubling of the'total areal extent of its average efentially of the wheel 50, is nearly equal to that of Fig."` 13 (compare Vthe arcuate arrows in the 'ZA areas), and is substantially greater than that of Fig. 14. This excess of circumferential length ofthe ZA area in Fig. 12 over that of Fig. 14

-is more than'twice the shortage in'that respect as between `Fig.'12 and Fig.' 13, in the ratio of about Sto 4. In brief, our major effective contact or average speed area ZA is both long and wide and hence more extensive than one of Aabout equal length but narrow (Fig. 13) or of about equal width but short (Fig. 14).

Another feature of advantage in our 45 construction of Fig. 12 concerns the size of the central angles e and the position and'extent of the respective ZA areas relative to the subtended sectors. Said angles, in Figs. 12, 13 and 14 re-y spectively, are 35|-, 39" and 28. Thus the angle e of Fig. 12 is about of a size with that of Fig. 13, and is one-fourth again larger than that of Fig. 14. As previously stated, these angles are determined by radii drawn through those points of the total contact bands Z which are the farthest spaced circumferentially.

In Fig. 12 said determining points are -well within the stipled ZA area, in the radial direction, while in both Figs. 13 and 14 they are wholly without said ZA area, toward the disk center C-54, substantially more so in Fig. 14 than in Fig. 13. Hence in our constructionv of Fig. 12 a larger area of the subtended sector of the abrasive wheel is active at a given moment; further, the longest arc of such active sector portion is substantially central of our ZA Zone. Thus the average-speed active area is not only larger but also is more symmetrically disposedy and balanced. And since in our case the average speed or uniform action area ZA covers a greater proportion of the total contact band area Z, being actually almost twice greater in proportion than in the other constructions, it follows that a given job may be satisfactorily completed in less time and with less wear of the abrasive element. I

Otherwise stated, the proportion of they total contact band Z outside the uniformity area ZA is materially less in our construction than in the others, 'as is seen by comparing the extent of the hatched but non-stipled areas of the three diagrams. And it is important than in our case said clear-hatched portions of the Z band rapidly decrease in extent as they approach the two opposite extremes of lineal spe'ed-of-grind variation,

that is, as they approach the inner and the outer arcuate connes of the total abrasive Zone R., In other words, the major part of these substantially triangular clear-.shaded Z portions of Fig. 12 are adjacent the uniformity zone ZA. But in contrast with this, both in the Fig. 13 and the Fig. 14 constructions, substantially the reverse is true, and the relatively large sections of the Z bands lying outside the ZA area. as represented by the hatched but unstipled sections, are of their maximum circumferential extent substantially or fully to the inner and outer limits of the total abrasive zone R. Y

Thus Figs. 12 to 14 clearly indicate diagram,- matically that with our novel construction a relatively inconsiderable part of the total grinding effort is carried out at either of the extremes of the different lineal speeds, that is, either in the region nearest the wheel center C-54 or in that most remote from it. In a word, our invention affords a materially greater uniformity in the lineal speed of abrasive contact over substantially more of the total contact area upon `the face of the abrading wheel.

Further, with the machine and method of our invention the dust or waste particles of material from the abrading element and the shoe lining vare carried off most effectively. There is little or no residue in the wheel housing, and very little dust escapes to clog and wear the machine or to accumulate Lon adjacent various other factors involved the dust particles are swept out through the lateral outlet 150, vpreviously described, with a minimum distortion of orl obstruction to their natura-l path Iof-'traveL saidgoutlet ,having i'ts axis Aat approximately a 45 angle to the wheelzradius central of Vthe work, 'andgaccordingly in the example shown being substantially horizontal, The efficiency of thisV action is 'such that no' supplemental vsuction or blowing eifort 'is needed, even 'in the absence of varies at 'the rear face of the abrading wheel, although :such maybe provided. Aif desired, as 'indicated `forV example at 5.2jin Fig. 4d. Said 'dust outlet '60 is in closed communication with a dust .receptacle Idisposed at'any convenient location.v

The 'terms abrading and vgrina'zling are herein employed generically ,and will be understood .as inclusive of cutting, .burnishing polishing lor other nishing action v.upon-lined arcuate brake shoes and 'the like for automotivecand similar purposes. i o

Our invention eitheras to methodor .means Ais Vnot .limited to the steps Aor ,structure as ,herein 'i described or illustrated byw'vay of example its scope being .pointed -.out in .our .following claims.

, We claim: .Y Y l Tl. .In a brakeshoenisher., a bed, a .longitudizfnal 'guideway at the rear portie-nef the b ed, .a .motor-driven rotary ,abrasive unit including a base mounted on the bed for movi-:ment along said way, an adjustingscrew shaft carried by the .bed Yancll 'having threaded engagement lwith .the

abrasive ,unit ybase `for advancing y0r retracting 1 said unit, lthe-bed havinga horizontal wallalong said guidewayand the abrasive .unit base Yhaving a `portion extending Ydown through the guideway and below said wall, a .plurality of frollerson Va transverse shaft .in `.the bed and adapted .toiengage the underface :of said `Wall, v at'r'least -oneroller member at each sidecf the ,iguitlevvay` means ,on `the Adownwardly extendingbase portion position- Ving the `roller shaft lengthwise .of .the bed, and spring means between said .shaft and the abra- ,o sive 4unit bedacting :to urgelthe shaftand rollers upwardly andthe abrasive unit downwardly into .-rmlyyseated yposition .on Vthe bed.

2. A brake .shoe finisher comprising a1bed',.`a

shoe'carrier assembly lmounted toswngabouta y -Xed vertical axis at `the .front portion. of the bed,

ai motor-.driven yabrasive .unit mounted .to have Aadjusting Amovement :on `and lengthwise `of the bed, the latter including upright frontend rear walls `and connecting -side wallssdening achamber, the abrasive unit `having adependinglportion ,in said chamber, an adjusting screw shaft inthe said chamber `and having threaded `connection with the Adepending :portie-noi .the .abrasive unit,

.supporting the shaft with capacity :for bodily 'axial movement thereof, a hand operating .niemiber :and-scale and Vindex means -atcthe front end Yof :the lshaft voutside `the bed, 1the shaftending short :ofthe `rearwall:` of =.the,bed a sleeve threaded ioA through .said rear wall inline with the shaft, and

a 'block having a threaded rear portion extending through `said Asaid sleeve and of a length .Pen vmtting 'the block to be rotatably adjusted variably to position it lengthwise V'the bed, said block adapted to have abutting and supporting engagement with the rear endof the shaft, adjustment of the block serving to Vary correctively the posi..- tion of the abrasive unit corresponding to a given reading of the ,shaftdial j l 3. In a brake-shoe nisher, a bed, a longitudinal guideway at the rear portion .of the bed, a motorf-'driven rotary vabrasive unit including a Joa-se mounted on the bed for movement along said Way, an .adjusting screw sha-ft carried by the -bed .and having threaded engagement with the abrasive unit base Ifor advancing .or retracting said i1-nit,mean`s on the bed supporting the shaft 'for rotation and also bodily shifting movement axially, .spring mea-ns normally urging the shaft .and abrasive unit rearwardly into the given posi tionof adjustment .as determined by rotation lof the shaft, an abutment on .the shaft, a cross shaft journalled in the side walls of the bed behind .said abutment and having at least one .end Pro,- ijecting laterally outsidethe bed, Aa :cam device fixed Von the cross sli-aft and engageable with the shaft abutment so as to move vthescrewshait.and abrasiveunit bodily forward for skiving the ends of a brake shoe fliin-ing, and an operating flever vfixed .on `said crosssha-ft and extending forwardly to a 1position .convenient to the operator, the cam device-and said levez` 'being constructed and pro por-tioned to afford a substantial leverage whereby said vsliivifng operation is readily manually controllable at the will ofthe Aoperator.k

4. In lamachine oflthe class yand `torthe pur .pose:described; abcd, ashoe carrier assembly mounted toswing about a vertical pivot'on the beati-fand an `abrasive wheel lon the bed rotatable vin a vertical plane transverse o f the bed, said `carrier assembly including a holder element for @presenti-ng Ithe vshoes to the abrasive wheel for i swinging! iacross its operative face in abracing )relation 'to it, `said holder element having `an in- -Wardly projecting shoe-receiving portion having imeansfthereon for supporting engagement lwith theund'ei l"faceof a shoeweb and also having relvatively ixed inner endabutments for positioning abutment against fthe inner face of` the arcuate flanged-f the shoe solely at `points spaced `laterally to either side of the central Yradius of the shoe, said abutments being shaped and arranged for conforming abutment with all diameters of shoes withinthe range ofthe machina-said holder elefment .thereby adapted -fo-r universal mounting of rdifferent sizes of-shoes'withinthe capacity ofthe ,given jma-chine. l

i5. -In ia machine of the class and forthe'purypose described, a bed, a shoelcarrier assembly Vmo'untedto swingabouta'verticalpivot on the bed, -andan abrasive -wheel on `thebed rotatable in a `vertical plane transverse of :the bed, said carrier assembly including a holder element for present- Aingthe shoes to the abrasive wheel for swinging across lits operative fade in y,abrading relation to it, means op `.the .holderoelement for positioning `a .shoe .in .the .direction axially ,0f the abrasive wheel and forsupporting i-tsolely by its web and with .the latter substantially horizontal, 4an :11pright ,post .on Athe ,holder element, `and a .unitary [clamping member .apertured for positioning .re-

ception on said ,post, said-clamping member having .angularly `disposed forward portions adapted f0.1 -lampine :engagement downwardhf .upon the 

